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Team NAXJA King of the Hammers preperations

Goatman

NAXJA Forum User
NAXJA Member
Location
Bakersfield, CA
We'd like to post up some tech about getting our rigs ready to race in King of the Hammers. If anyone doesn't know what King of the Hammers is, it's a combination desert race and rock race, a formatt that has never been done before. We were very happy to be included in the first ever race of this type, and even happier to finish in the top 10. Last year (actually Feb '08) was about 40 miles of desert and 10 miles of hard rock trails. We were fortunate enough to come in 7th out of 43, even after breaking a driveline and air locker lines and being down for about an hour.

I'll start with some things we did to prep the car for last years race. We added safety items including window nets and door bars, and a battery/engine kill switch, and a wide angle rear view mirror. Suspension wise we added 2" Fox air bumps to the front, with 3" of bump travel, and worked on the coilovers some to fine tune the secondary rate transition point. We also added 1/2" steel rings from Staun to the inside bead of the steel beadlocks, to help prevent bending the rim on the inside, and got a set of 40" Maxxis Creepy Crawler stickies. I beefed up the motor mounts by expanding the mounts to include 5 bolts on the block instead of just the 3 for the stock mounts. Rigwerks supplied a very beefy crossmember/belly pan. We prepped the car by beefing up some of the front suspension mounts, beefing up and double shearing the pitman arm, and going through the rig and tightening every bolt to proper torque using a torque wrench, and marked all of the suspension and steering bolts so we could see if they loosened. Also worked on all the vent lines to insure we'd have no leaks in case we rolled.

The one thing we didn't do was reroute and protect the air locker lines from heat. Running flat out generated much more heat than we were used to and melted sections of the lines, causing us to loose our lockers, which then led to breaking the CV in the rear driveshaft. Our crew brought us the spare shaft, and fixed the air lines, but we lost an hour.

Here's some pics of the rig ready for the last race.

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I wasn't happy with the ride and handling of the rear suspension after the last race. With the light rear weight, I already had the lowest rate springs available, and it was still too stiff. I also would end up needing air bumps, and I didn't see how it could be done with the configuration of the rear of the buggy. Air shocks seemed to do well last year, the 1st and 2nd place rigs had them, so I decided to try a new brand and type of air shock from ORI in the rear.

http://www.oristruts.com/

My buggy was built for crawling, not for speed, and I built it with really high roll centers. That works exceptionally well for crawling, it's extremely stable, but the rear didn't work real well at speed because the panhard mount was too high on the axle. I had already lowered it a couple inches for the last race, but we lowered it another 3 inches. Because the panhard bar had too much of an up angle as the suspension compressed, it caused a slight twisting action that created lift on that side so the passenger side wouldn't bottom all the way out no matter how hard we hit.

Lowering the panhard mount worked great, now it bottoms out evenly. And the ORI's made a huge difference, we can make it as soft as we want, and control the stability (which is already very good). The rig rides and handles at speed MUCH better than it did before.

Here's a pic with the new ORI Struts.

100e4620.jpg
 
In the last race, our top speed was 3200-3300 rpm, which comes out to just over 80 mph. That's as fast as it would go. We need more speed, more acceleration, and more throttle response. I'd really like to build a stroker, but can't afford it yet, and I wanted better rpm at the top end, so decided to do a gear change. The rig has 4.56 gears, which isn't the best with 40's and low air pressure. We're going to run more air next race, which will help a little, and we're changing to 5.13 gears. That will move us up to 3700-3800 rpm at around 80 mph, which is a much better power band. It should give us much better throttle response and more speed.

Since the HP60's are known to break gears in the rear when used hard, I sent the new gears to Performance Cryogenics to get them cryo treated, which makes them tougher. We installed the rear gears on Sat, and fronts go in next Sat.
 
sweet merciful jesus... You have the gall to put Cherokee XJ on the side of that beast?
In all seriousness though - that is a gorgeous piece of fabrication. Best of luck in all your prep & racing! Keep us updated!
 
Richard, it seems like many guys prefer a triangulated four-link for their crawlers. After changing the panhard mount on the rear axle, is there anything else you would change?

Starting from a pile of tube again, would you still do the three link with panhard?
 
Richard, it seems like many guys prefer a triangulated four-link for their crawlers. After changing the panhard mount on the rear axle, is there anything else you would change?

Starting from a pile of tube again, would you still do the three link with panhard?

From the passenger seat I see no downside to the rear 3 link. With the high rollcenter it's 'suppose' to be more stable on the trail & harsher on the fast, but with the new shocks Richard's feels great on the fast. There is no hint of a trackbar or 3 link when going fast, at least not that I noticed.

Paul
 
Sick...good job on that thing!

~Scott
 
sweet merciful jesus... You have the gall to put Cherokee XJ on the side of that beast?
In all seriousness though - that is a gorgeous piece of fabrication. Best of luck in all your prep & racing! Keep us updated!

I'm sure the VIN is still on the firewall, so technically as Cracker's plate on his buggy says, "STILLNXJ", besides, I'm going to win the buggy ride at goat fest and see how strong it really is. :)
 
Richard, it seems like many guys prefer a triangulated four-link for their crawlers. After changing the panhard mount on the rear axle, is there anything else you would change?

Starting from a pile of tube again, would you still do the three link with panhard?

I love 3 links, I did one in the front of the XJ when no one had done them (wow! that was more than 8 years ago), comp rigs didn't even have them then, and I've always been real happy with it. Now, there's 3 links all over the place in all kinds of rigs.

It's hard to say which is prefered, 4 links or 3 links, there's a ton of both on rock crawl buggies. Some have done 4 links because they didn't understand 3 links, or thought there was something inherently bad about a panhard bar, which there isn't. All moon buggies are 3 link, and there's plenty of moon buggy style rigs doing well in XRRA rock racing. The 1st, 2nd, and 4th place rigs in the last KOH race had 3 links front and rear. It was thought in advance by some outspoken internet folks that air shocks and 3 links wouldn't work when speed and distance where involved, but that thought was proven drastically wrong, as those rigs with 3 links also had air shocks.

Other than the panhard mount location on the axle, there's nothing I'd do different about the rear 3 link. We know that they excel in rock crawling, with great stability and simplicity. A 3 link needs to be configured slightly different for speed than for what can work really well in rocks. However, since I've lowered my panhard mount, it hasn't seemed to loose anything in the rocks. To know that for sure I'd have to run the same lines on the same obstacles for a better comparison. One reason I went with the ORI's was to compensate for any stability that I lost by lowereing the panhard, but I think in reality it hasn't made enough difference to notice.

A 4 link can be configured to work well for both crawling and speed. If I was to start over, with more speed in mind, I might consider a 4 link if I really wanted to increase the rear travel, which would also mean a big increase in front travel. It's yet to be seen if a buggy with travel around 20" can be stable in the rocks, and be a real good crawler and climber. We'll have to see as more longer travel rigs are built for KOH. We also haven't seen a 20+" travel 3 link, to see what kind of handling and stability it has. Lots to learn yet.

We're much faster than were before, in the last race, and we can be faster still, so right now I'm pretty happy with the 3 links.
 
You get too much faster, you're going to win the darn thing and make everyone look bad. :)
 
You get too much faster, you're going to win the darn thing and make everyone look bad. :)

Don't have a stroker yet. :D





Keep buying those T-shirts. :)
 
Richard, do you have full hydro, or hydro assist? Did you have any cooling problems with them on the last race?

I remember that being a big problem for several of the other competitors.
 
Richard, do you have full hydro, or hydro assist? Did you have any cooling problems with them on the last race?

I remember that being a big problem for several of the other competitors.

I have hydro assist. I've wondered about going full hydro, but I have so much money into the assist and it works so well, I'm going to stick with it. The steering input and control is very good, quick, and absolutely stable at speed. I can turn with one hand in any situation, so it has plenty of power. I didn't have any heat issues during the race, or at any other time.

My system consists of all Tommy Lee (Lee Mfg) parts except the ram and pump pulley, which are PSC. A TC pump that Lee rebuilt and modified, Lee rebuilt steering box, Lee remote reservoir and inline filter, PSC 4.5" pump pulley, and PSC 8" x 1.75" ram. It has two of the smallest size Hayden trans coolers.

The steering is also sharp, the arm distance from the ball joint centers is only 6". This also makes the steering fairly quick, and sharp enough that I had to grind to clearance the inside of the axle yokes.
 
Richard, Dave & I have been doing a lot of KOH related shock tuning & testing this past year. It's been a lot of fun & real rewarding, so I thought it might be interesting to share, especially our unexpected & unanimous conclusion.

Our primarily goal has been to improve the fast stuff. We kept an open mind, looking at how our different cars worked in the desert & seeing how we could improve them.
Our biggest struggle has been how to improve the fast stuff without sacrificing the slow stuff.

We (Richard) pulled the fastest time of anyone on arguably the hardest trail section of KOH 08, we’d definitely like to repeat this in 09, so giving-up trail performance isn’t an option.
Our speed in the desert was ‘competitive’. With a lot of tuning we could get a little faster, but primarily we could get a lot more comfortable & thus conserve energy for the technical sections (I still don’t know how Richard had the concentration to run the whole race with only one diff grabber related back-up).

As you know, Richard had coilovers f/r + air bumps up front. Richard swapped springs & revalved several times, right down to total disassembly on the lakebed so we could experiment with different valving through the weekend.
We got them working a lot better than they were for KOH 08, but we knew we could do better & we couldn’t see getting there with coilovers. The problem that we kept bumping into was getting them stiff enough to handle the baja type stuff & soft enough that we could scoot up the trails & not thrash us in the in between stuff.
On to air shocks… as their progressive way does exactly what we need.
With this thought, Richard picked-up a pair of ORI’s for the rear. Right out of the box these made a huge improvement, it had to be twice as smooth as before. By the Rockin jambo he’ll have a set of ORI’s for the front & I expect that with just a little tuning Richard’s junk will be smokin. I’m a happy co-pilot.

Dave’s junk has been for a couple of years the fastest in the desert (in our group), this with 2.5” airs up front, coilovers rear + air bumps f/r. It’s real smooth & I doubt that we’re going to get any faster with our stock 6’s. However, Dave’s front has always worked better than the rear, so he’s spent his time trying to match the rear to the front. Last month he was finally ready to ditch the rear coilovers in favor of 2.5” airs, but at the last minute he lined up a deal on some new Kings (wait till you see these things).
He’s already cut off the f/r air bumps & I don’t think he’s going to miss ‘um.

I’ve been running 2.5” airs p front, which have worked great with very little tuning (exact same as Dave’s). As good as they were, last month we decided to make a major change to see if we could make them better suited to a possible 100 mile KOH (at the time we thought Dave would still have his Fox’s for the race). Somewhat to our surprise, it worked. With the change they became about 10% smoother & they no longer change height after long desert runs. Before the change they never faded, but they did increase in height after a long, fast desert run.
I was running 2.0’s in back & tuning them after every run. At times it was fairly ok, at other times it was terrible. I just couldn’t get the 2.0’s to do it all. In September I replaced them with 2.5’s & after just one weekend of tuning they were working great. I then revalved them at home before taking them out for the 2nd time, this time out all of the whoops on our little test track disappeared completely.

So, that takes you from where we were to where we are & where we’re going.

It’s going to be a lot of fun seeing how the new ORI’s & Kings do. I think the bar is about to be raised yet again, we might need those strokers after all:D

Can’t wait for KOH 09…

Paul
 
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